1. Field of Invention
This invention relates to a water purification apparatus and system for aquariums and particularly to a system including external filter means in combination with a submerged member for promoting bacterial decay of waste particles.
2. Description of the Prior Art
It is recognized that nature's process for the purification of contaminated or polluted water generally occurs through the combination of a natural filtering system for the flowing or percolating water in combination with biochemical and/or bacteriological decay of the pollutants. In the normal aquarium environment, it has proven difficult to obtain the requisite balance as between bacterial growth to promote bacteriological decay without excessive build-up of bacterial colonies which make the water turbid and unsafe or the excessive build-up of the pH and toxic materials while providing proper filtration to remove particles not readily attacked by the bacteria, e.g. large size waste particles, from accumulating in the aquariums. Without the ability to provide proper purification, frequent time consuming cleaning and change of the aquarium water is required to maintain a healthy and aesthetically pleasing clear environment for the aquarium.
Various attempts have been made in the past to achieve a balanced purification system, but none have truly met the mark. For example, in U.S. Pat. No. 2,769,779 a porous water purifier embedded in a sand filter is provided which lodges waste-burning and nitrogen fixing bacteria. Water is drawn through the sand and purifier by means of a suction tube outlet in the purifier. The suction is induced by an aerator placed in a cylinder which surrounds the suction tube. The purifier is an agglomerated mass of small particles e.g. ceramic or plastic particles bonded together to entrain the bacteria. In this system, no means are provided for eliminating waste particles which are not readily attacked by the bacteria. Further, there is a tendency for clogging of this system, bacterial overgrowth and/or the accumulation of ammonia and/or other toxins. Also, cleaning of the aquarium becomes cumbersome due to the presence of sand or gravel which must be removed and cleaned and/or replaced.
In U.S. Pat. No. 3,135,238 there is described a filtering system which includes aeration. Here, an external filter for entrapment of large particles is provided together with a porous base plate filter lying on the bottom of the tank and embedded in gravel for removal of fine particles. This system does not employ bacterial action and depends upon the use of gravel for part of the filtration process. Hence, no provision is made for neutralization or metabolism of ammonia and other biodegradable toxic materials.
According to U.S. Pat. No. 4,556,485 an under-gravel filter is also provided wherein the filter medium is the gravel in the tank. As indicated therein, clogging is one other problem associated with such filters. In addition to the gravel, an internally located removable filter material is provided to improve the filtration efficiency of the gravel.